Remove special handling of delete aa[key].

This has been an error for a couple of years, and has been deprecated since pre D 1.0.
Remove special handling of old .offset property
Remove escape string literal error and improve error message
Remove error for old .typeinfo property
Fix Issue 5299 - Protected inheritance is semantically undefined

Deprecation -> Error
Fix Issue 3990 - Deferencing a dynamic array as pointer

Deprecation -> Error
fix Issue 13400 - Linking problems with bigints and std.functional.memoize
Merge pull request #3912 from yebblies/issue3990

Issue 3990 - Deferencing a dynamic array as pointer
Merge pull request #3911 from yebblies/issue5299

Issue 5299 - Turn base class protection into an error
Merge pull request #3917 from yebblies/typeinfo

Remove error for old .typeinfo property
Merge pull request #3915 from yebblies/escapestring

Remove escape string literal error and improve error message
Fix Issue 4374 - Required do-while ending semicolon

Deprecation -> Error
Merge pull request #3914 from yebblies/removeoffset

Remove special handling of old .offset property
Fix Issue 2656 - Remove octal literals

Deprecation -> Error
Merge pull request #3929 from yebblies/issue4374

Issue 4374 - Required do-while ending semicolon
[Refactoring] Remove unused flag 0x100 in Type::toDecoBuffer
[Refactoring] Directly handle OutBuffer in Mangler
[Refactoring] Move type mangling code into mangle.c
[Refactoring] Move expression mangling code into mangle.c
Merge pull request #3916 from yebblies/issue2656

Issue 2656 - Remove octal literals